POS0315 DIAGNOSTIC PERFORMANCE OF CASPAR CRITERIA FOR PSORIATIC ARTHRITIS WITH OR WITHOUT INTEGRATION OF ULTRASOUND
Authors: Y. Geng, Z. Song, X. Zhang, X. Deng, Y. Wang, Z. Zhang
Journal: Annals of the Rheumatic Diseases (2022)

Background Although the CASPAR criteria in the diagnosis of psoriatic arthritis (PsA) have been validated, CASPAR based on physical examination (PE) is not “gold standard”. The ultrasound (US) could improve the diagnostic accuracy as compared to clinical examination alone. Objectives To evaluate the diagnostic performance of CASPAR criteria for psoriatic arthritis (PsA) with or without integration of ultrasound (US). Methods The patients with hint of PsA were enrolled. Tender and swollen joint counts, presents of enthesitis and dactylitis were collected by physical examination (PE). US was performed to evaluate peripheral joints, entheses and tendons. The additional value of US to CASPAR criteria were analysed. Results 326 consecutive patients were enrolled, with 164 PsA and 162 non-PsA. Significantly higher frequencies of tenosynovitis and enthesitis on US and new bone formation on X-ray were found in PsA than non-PsA patients (56.7% vs. 13.0%; 62.2% vs. 14.2%; 62.2% vs . 8.0%, p &lt;0.01 for all). Logistic regression analysis showed that dactylitis (OR=12.0, p &lt;0.01), family history of PsO/PsA (OR=3.1, p &lt;0.05), nail involvement (OR=3.5, p= 0.01), new bone formation (OR=14.8, p &lt;0.01) and tenosynovitis on US (OR=21.3, p &lt;0.01), enthesitis on US (OR=21.7, p &lt;0.01) were independent risk factors for PsA. Adding US tenosynovitis and/or enthesitis to CASPAR criteria showed better performance by improving the specificity (91.4% vs. 67.9%) and meanwhile keeping sensitivity (92.1% vs. 96.3%). When replacing hand X-ray by US in CASPAR criteria, the sensitivity and specificity were comparable to CASPAR criteria adding with US. The diagnostic accuracy was 82.2% for CASPAR criteria based on PE, 91.7% for CASPAR integrated with US, and 91.4% for CASPAR with US to replace X-ray. Conclusion CASPAR criteria based on US improve the diagnosis utility of PsA than CASPAR criteria based on PE. US assessment is valuable in the diagnosis of PsA. References [1]Fiorenza A, Bonitta G, Gerratana E, et al. Assessment of enthesis in patients with psoriatic arthritis and fibromyalgia using clinical examination and ultrasound. Clinical and experimental rheumatology 2020;38 Suppl 123:31-9. [2]Zabotti A, Bandinelli F, Batticciotto A, et al. Musculoskeletal ultrasonography for psoriatic arthritis and psoriasis patients: a systematic literature review. Rheumatology (Oxford) 2017;56:1518-32. Figure 1. ROC curves for adding US or substituting X-ray by US in CASPAR criteria. Receiver operating characteristic (ROC) curve illustrates the diagnosis performance of CASPAR criteria adding US or substituting X-ray by US in CASPAR criteria and CASPAR criteria based on PE alone. The area under the curve of the ROC curve (AUC) was 0.929 (95%CI 0.897, 0.961) (p&lt;0.01) for adding US to CASPAR criteria. AUC was 0.908 (95%CI 0.876, 0.940) (p&lt;0.01) for CASPAR criteria based on PE. And AUC was 0.916 (95%CI 0.880, 0.951) (p&lt;0.01) for substituting X-ray by US in CASPAR criteria. CASPAR: ClASsification criteria for Psoriatic ARthritis; PE: physical examination; US: ultrasound. Disclosure of Interests None declared